Ada County, ID Zoning Overlays & Bonuses: Density Bonus Law (2026)

Under Ada County Code 8-6-22(G)(3), the baseline PUD residential density is whatever the comprehensive plan establishes for the area; where the plan sets no urban density, the ceiling is three (3) dwelling units per acre. The County will approve a higher density only through the two bonus paths written into subsection (G)(3)(b). First, for every full additional percentage point of the project dedicated to open space beyond the code's minimum open-space requirement, the average residential density may rise by that same percentage point, capped at an additional 25% over the base density.

Second, a separate density bonus is available for dedicating land or facility interests as a "public amenity," defined in (G)(3)(b)(3) to include a school site, bike path, transit facility, park site, park-and-ride lot, or public safety facility (police, fire, or EMS). That amenity-dedication bonus is fixed on a sliding table rather than left discretionary: Table 8-6-22-1 pegs a 15% land dedication to a 5% density bonus, a 20% dedication to a 10% bonus, and a 25% dedication to a 15% bonus. All dedications supporting either bonus must be shown on the master site plan filed with the PUD application, and the Planning and Zoning Commission must make the findings in subsection (H) before it will issue the PUD, including that the project is consistent with the comprehensive plan and does not create undue adverse impacts on surrounding land.

A PUD application itself must cover at least five acres and lie entirely within an area of impact before any density bonus can be considered.